Radio Frequency Identification

Radio Frequency Identification

Róbert Schulcz (Budapest University of Technology and Economics, Hungary) and Gábor Varga (Budapest University of Technology and Economics, Hungary)
DOI: 10.4018/978-1-60960-732-6.ch023


In this chapter, we will start by briefly summarizing the history of radio frequency identification systems. After that, we will introduce the components of such systems and classify them based on programmability, data capacity, frequency, and reading distance, as well as power supplement and reply transfer methods. We will describe the various coupling types used in RFID systems, present the common coding schemes and modulations, and give an overview of the standardization efforts. This chapter will focus on collision detection and resolution algorithms and conclude by practical suggestions on RFID system selection for different tasks.
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Parts Of An Rfid System

A wide spectrum of demands can determine the set-up of RFID systems. A configuration consisting of a single transponder and a reader, as used in electronic article surveillance, may be regarded as the simplest RFID system. A more complex system can contain thousands of transponders, a number of networked readers, controlling computers and back-end databases.

Radio based identification needs at least two devices: one to identify and another that identifies the first. The identifying device initiates some kind of data connection with the other, during which data is transmitted in one or both directions. Communication is transmitted over radio frequencies, so both devices need to have radio interfaces. Therefore, a basic RFID system consists of at least the following two components:

  • A transponder that is attached to the object to identify

  • And a reader that is able to read and/or write the transponder

The above system, depending on the application, may be augmented with a controlling computer, which might be harmonizing the work of multiple readers and linking the readers to back-end databases. The devices between the reader and the end application are referred to as middleware. The back-end databases store information about the transponders in the range of the readers. Information can be queried, but also updated during data transmissions. (Want, 2006)


The reader's goal is to establish a radio connection with the transponder, identify it, and to establish, maintain and close the data connection, during which the reader and the transponder exchange information. According to this the reader always contains an RF module (transmitter and receiver), a control unit and connector interfaces to inter-operate with other systems. Common connector types include RS-232, RS-485, Wi-Fi, USB, etc. Most readers have internal antennas, but the more expensive ones have ports to attach external antennas too. Readers might also be referred to as interrogators, emphasizing their initiative role in the communication.


The RFID transponder holds the information assigned to the product or tagged item. It consists of a microchip and an antenna, and it is usually mounted on some rigid or flexible carrier object. The information can be a unique identifier, a manufacturer ID, product code, or any other data. The transponder might also be called an RFID tag or label (Figure 1).

Figure 1.

Parts of an RFID system

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